This invention relates generally to processing digitally stored images. More specifically, it relates to processing image data retrieved from a low precision image scanner to a normalized high quality digital image.
In photographic arts, as computer technology became widely available, it became possible to electronically scan the film image to a stored digitized electronic image in a computer system. Once the images are digitized, they may be archived, edited, enhanced or otherwise processed digitally.
High resolution scanners use an array of sensors arranged in a line which is mechanically moved across an image. The eye can detect jitter of less than a quarter pixel requiring, with a two thousand element array on a 35 mm film, mechanical accuracy closer than five wavelengths of light. To achieve this accuracy, current state-of-the-art scanners rely upon high precision registration and handling of the substrate, e.g., film, on which the image is placed past the scanning optics. Quite naturally, the precision hardware is also quite expensive. Nonetheless, high quality image data is retrieved and digitized.
It is desirable to produce a low-cost scanner available for personal use in business, home, and school. One obvious way to make a personal scanner less expensive is to replace the expensive image handling hardware with less expensive low precision hardware. However, low precision hardware will result in scanned images with inconsistent vertical and horizontal spacing as the motor which is used to move the image substrate past the scanner, slows down, speeds up or possibly even reverses in direction. Other errors can be induced from the shifts of the substrate within the hardware. Thus, in a scanner of this type, it will be necessary to provide a number of modifications and corrections to reduce the raw data to a normalized form consistent with a high quality image.
The present invention provides a logical queuing scheme to allow the corrections and adjustments to be made on the raw scan data to reduce it to a corrected and normalized form.